Acid Mine Drainage (AMD) is produced when sulfide-bearing material is exposed to oxygen and water. The production of AMD usually – but not exclusively – occurs in iron sulfide-aggregated rocks. Although this process occurs naturally, mining can promote AMD generation simply through increasing the quantity of sulfides exposed. Naturally-occurring bacteria can accelerate AMD production by assisting in the breakdown of sulfide minerals.

AMD causes:

When mineral deposits that contain sulfides are mined, they have the potential to produce acid mine drainage. This includes the mining of coal, copper, gold, silver, zinc, lead, and uranium. The mineral pyrite, more commonly known as "fool's gold," is iron disulfide (FeS2). Pyrite is one of the most important sulfides found in the waste rock of mines. When exposed to water and oxygen, it can react to form sulfuric acid (H2SO4). The following oxidation and reduction reactions express the breakdown of pyrite that leads to acid mine drainage.

1. 2FeS2 + 7O2 + 2H2O -> 2FeSO4 + 2H2SO4

2. 2Fe2+ + 1/2 O2 + 2H+ -> 2Fe3+ + H2O

3. Fe3+ + 3H2O -> Fe(OH)3 + 3H+

4. FeS2 (s) + 15/4 O2 + 7/2 H2O 4H+ + 2SO4- +Fe(OH)3 (s)

Production of acid mine drainage can occur long after mines have been abandoned if piles of waste rock are in contact with air and water. The red color often seen in streams receiving acid mine drainage is actually a stain on the rocks called "Yellow-Boy," or ferrous hydroxide (Fe(OH)3) formed during Reaction 3 above.

Acid Rain:

Acidic deposition, or acid rain as it is commonly known, occurs when emissions of sulfur dioxide (SO2) and Ox-ides of nitrogen (NOx) react in the atmosphere with water, oxygen, and oxidants to form various acidic com-pounds. These compounds then fall to the earth in either dry form (such as gas and particles) or wet form (such as rain, snow, and fog). Prevailing winds transport the compounds, sometimes hundreds of miles, across state and national borders.

Acid rain causes:

Power plants, industrial manufacturing, and motor vehicles are all sources of pollutants that are ingredients of acid rain. These pollutants become part of the air masses circulating in the upper atmosphere, which flow predominately into the Northeast. The industrial Midwest is responsible for about half the sulfur dioxide emissions east of the Mississippi. The state of Ohio produces two times more tons of sulfur dioxide than all of New England, New York, and New Jersey put together. It is pollutants from these distant sources that contribute to damages in the Northeast environment.

These excerpts most accurately convey my understanding of these two different problems. I didn't look long...just for "quips" that felt I most agreed with.

So my question is ( and I kind of cruised thru most of this thread) what is the question? argument? disagreement here? And just in case Pat answers...give me the short version. I'm just passing thru.

Tom, the things you posted are consistent with what Pat, Chaz, and myself were saying. It also does not contradict the author in the OP. If by argument, you mean Dwight not accepting what we have been saying, it is restricted to the part that I highlighted in the text below. He doesn't believe this could happen in nature. Afterall, all things bad are man made, right?

It is a point not mentioned by said author and often overlooked. I only brought it up because one of the streams mentioned in the article reminded me of it. I have since grown to regret bringing it up. It distracted from the original point which is the larger problem in a large majority of cases.

Quote:

tomgamber wrote:[i]AMD:

Acid Mine Drainage (AMD) is produced when sulfide-bearing material is exposed to oxygen and water. The production of AMD usually – but not exclusively – occurs in iron sulfide-aggregated rocks. Although this process occurs naturally, mining can promote AMD generation simply through increasing the quantity of sulfides exposed. Naturally-occurring bacteria can accelerate AMD production by assisting in the breakdown of sulfide minerals.

Things not being argued about in this thread are:

1. Disturbing the stuff through mining, drilling, or whatever exposes MUCH more of it. Orders of magnitude more.

2. Acid Rain is still a problem especially in areas that have very little to no buffering or are even somewhat acidic by nature. (see article.)

It does happen in nature...one of the other excerpts I read and I'll post it if I have time, referred to Acid Rock Discharge. Its is an ongoing process though and the stream would be acidic for a longer, in geological terms, period of time. It would not happen suddenly unless of natural erosion exposed a previously unexposed acidic formation and even that would slowly increase the streams acidity. It would be much more difficult to remedy if someone felt the need to do so. It may also be why some PA rook trout have a natural tolerance for a certain amount of acidity.

I live in Central/Upstate, NY about 25 miles south of the Adirondack Mountains. Cornell University has been working for many years in the Adirondacks to try and get the PH in many streams raised. They too have been saying about the acid rains coming from factories across and along Lake Ontairo. I think it has just as much to do with all of the logging that went on here 100+ years ago. There is very little topsoil in the Adirondacks so therefor very little filtering can go on from the time the acidic rain hits the soil until it hits these small streams. Hopfully over time and as forests mature again they will be able to build up their own organic matter on the forest floor to help purify the acid rain. I am a golf course superintendent and I know from experience that turgrass prefer pH levels around 5.8 to 6.4 depending on the variety. Which is interesting to me that fish seem to prefer it around the same.

hi, bigDAKattack here. I hunt along E Millstone, and want to fish it also. Ran across some kids doing water samples for classes at Penn State yrs ago. They said nothing should be living in there. Didn't quite understand what they meant? I have seen some acid drainage seeps entering the creek about 1 1/2 miles up from Loleta swimming area. Is the ph that bad? What can we do as sportsmen to help bring the creek back? Please email me.

PAgeologist wrote:@pcray-I am not arguing against acid rain being the cause, or that acid rain doesnt exist. I am also well aware of the lack of good extensive buffering formations in western PA. The limestones in western pa are generally freshwater formations and have far less buffering capacity than the marine limestones in central/eastern PA. My problem with the article was that it didnt eliminate the other causes of a dead stream and jumped to the conclusion that it was acid rain. Perhaps he did his investigation correctly and didnt publish the data? Its poor science at best if he didnt at least explore other possibilities.

You can tell from the chemistry of the stream if it's impacted by either AMD or Acid Rain right?

chaz: "You can tell from the chemistry of the stream if it's impacted by either AMD or Acid Rain right?"

question not asked to me, but acid rain & AMD may both depress water pH. however, compared to acid rain, AMD may produce elevated conductivity from point discharges such as small mine-affected seeps. AMD may also lead to more orange rock coating.

if you look up the PSU schrader creek study readily available online, that area has both AMD and acid rain effects. they walk up tribs using simple conductivity guages and locate small seeps with AMD. above them, the conductivity sometimes fell sharply. see the psu conductivty walk of long valley run, for ex.

acid rain impacts would be influenced by the buffering capacity of bedrock geology, and impacts would probably not change as much from small seeps.

k-bob wrote:chaz: "You can tell from the chemistry of the stream if it's impacted by either AMD or Acid Rain right?"

question not asked to me, but acid rain & AMD may both depress water pH. however, compared to acid rain, AMD may produce elevated conductivity from point discharges such as small mine-affected seeps. AMD may also lead to more orange rock coating.

Agreed. The researcher can tell by the conductivity, metals, abrupt pH changes, noticing land disturbances, knowing the environmental history of the watershed, knowing the geology (where coal exists and where it does not), etc.

The researcher was a professor at Clarion. Assuming that he would not be aware of AMD if it was present is not a good assumption.

He probably didn't mention AMD for the same reason that he didn't mention paper mill discharge. Because it's not there.

@Chaz... Yes you can tell the difference between waters affected by acid rain and mine drainage. Both result in lower pH values. The difference is in the elevated concentrations of metals (in particular iron, manganese, and aluminum) and sulfate, which will be present in mine drainage. Most of the time you can see the metals and sulfate precipitation but not always.

There are exceptions though. Not all mine drainage is acidic. Some discharges are alkaline but they still have the high concentrations of metals.

Posted on: 2015/1/3 11:08

_________________
"Distrust any enterprise that requires new clothes"-Henry David Thoreau